The present invention is related to system and method for correlating optical micro-tremor signals with cognitive dysfunctions, and more particularly to a signal acquisition subsystem for obtaining at least one ocular micro-tremor signal, a signal processing subsystem for creating an ocular micro-tremor waveform and a correlation subsystem for comparing the ocular micro-tremor waveform to either a set of waveforms from populations of “normal” or fully functional cognitive individuals, or those of various classes of cognitively dysfunctional populations.
Advances in imaging technologies, along with a focus on the importance of cerebral processing in medicine and computer development during the last two decades, have provided the framework for many new approaches in both the theory and experimental data pertaining to the mind/brain interaction. During this period, newly formed departments of conscious awareness and cognitive science have appeared at university centers worldwide. Together with institutional research and development projects, scientists and philosophers from many disciplines have joined this quest: How indeed does the human mind perceive reality, form though and reason, and experience qualitative emotion through the elements of cognition? Much of the research has centered about developing an understanding of consciousness, and the role of awareness within that process.
The systems' architecture that would be required to meet these criteria could include brain matter proximal to the terminus of the neural switches, capable of storage of data through a quantifiable physical mechanism, and conductive within its own right. The latter requirement would be necessary to produce ongoing communication between neural segments, as the synaptic junctions would now only be switching networks. As will be pointed out below, this material could easily be postulated to be the brain's own support matter, the local glial cells. More importantly for the moment, the flow-down requirements on timing imposed by the second criteria on the mind/brain architecture requires expansion. The need for periods of off-time within the cycle of producing thought, recalling or storing memories, primarily related to sorting or finding facts probably fits comfortably within our own realms of experience. This type of general architecture could be constructed by postulating the existence of a master “process clock,” against which all perceived cognitive events could be referenced. This may not be necessarily surprising, since other organs require timing periods for their operation such as the various muscle functions of the heart and peristalsis within the intestine.
The brain's intrinsic timing would have to allow for data input, retrieval, encoding (establishing a mechanism to allow it to be re-interpreted) and then de-coding. During these physical processes (some of which could conceivably be done in parallel within topologically non-coincident sites in the physical brain), a bifurcated periodicity must also exist where the brain is conscious-and-aware vs. conscious-but-unaware of underlying processes or choices. These two states are not dissimilar to the terms of consciousness or subconscious. The labeling is forcibly highlighted as always conscious, but aware part of the time, and unaware the rest of the time, to emphasize both the periodicity and exclusive need to have both states allowed with a continuous stream of data storage and recall. The unaware state is a definite requisite to accommodate the de-selection process discussed previously. Without it, one could be conceivably lost to the dementia of listening and/or seeing all the alternatives we have to pick from. Because of the fundamental requirement of having no dynamic memory manager, the conditions of awareness and unawareness cannot run simultaneously without the aforementioned cerebral process timing. Otherwise, it would take a cognizant function to know when to switch between states, and therefore, an a priori cognition of what conscious choice was to be made—a Herculean feat even for quantum mechanics.
A model proposed herein includes rapid blending of both states at the gamma band frequencies, typically centering about 40 Hz wherein the contents of consciousness are fused in much the same manner as the visual flicker fusion, audio fusion and tactile stimulus fusion experiments described earlier. To simplify terms, the process will be referred to as cerebral fusion. The contents of the cerebral cortex, as either experienced from the body's external sensors, or as perceived from memory and replayed through virtual sensor sites in the brain, integrate completely to form an ongoing vignette of scenes, thoughts and emotions. The systems description must further postulate that in no event can the mind sense the discreteness of the events. Complete continuity of consciousness at these cerebral process clock rates would prevent individuals from ever comprehending the detail between the windows of awareness. On the other hand, this same mechanistic process would allow for the appearance of simultaneousness between sounds and images occurring between temporally adjacent windows, even though we know that some audio stimuli arrive sooner to the cerebral cortex than do visual signals. Essentially, with the process of cerebral fusion, events can occur discretely, but near enough in time, and are captured during either an aware or unaware cycle (within about 20 to 50 msec). It is proposed that the mind will not discriminate between the separateness of the events, insofar as in this fusion process, the evolution of adjacent windows provides the illusion of continuity of thought. This concept is not dissimilar from the often-discussed binding problem.
Cerebral fusion may have three fundamental properties that allow for both blended information processing, and the observed sensory stimulation to perception delays. These properties are globalization, integration and persistence. Globalization refers to the ability of the cerebral workspace to respond to those areas across the cortex containing features of current thoughts. Since the fragments of pictures, words, associated smells, memories and sounds are not necessarily topologically co-located, the active centers contributing to an aware moment must be accessible to a centrex of processing (perhaps, the thalamus), much like a planetarium with a series of highlighted elements. This is conceptually not very different from a global workspace, with its attendant spotlight on the most current neural locations corresponding to the contents of a thought. At this juncture, no statement is made as to the interpretation of the discrete data items into recognizable images or sounds; what is implied within the globalization process is that all excited neurons are globally accessible and as such, are momentarily “highlighted.” Integration refers to the process of assembling the quanta of thought elements described in the globalization process. As already discussed, together with the process of cerebral fusion, integration is a temporally driven capability of the brain wherein it is not possible for us to distinguish the non-simultaneity of successive events within one window of consciousness. The integration process guarantees that some fixed amount of time will be necessary post sensation before we are either partially depending on the elements currently undergoing globalization, or totally aware of what is occurring in the mind (or within the spotlight of the global workspace). At this juncture, integration assures that the recognition of already known or selected items can be made, but does not preclude the non-recognition effects of new items as well. Additionally, integration during unaware cycles allows for the de-selection of unwanted materials or intermediate results, as described earlier.
The establishment of a persistence component to cerebral fusion refers to a capability of individual neuronal sites to retain, with some finite lifetime, the contents of their stimuli that are undergoing integration during any one window. The observed nature of how human thought is continuous would require that sites be active for at least adjacent temporal windows (no less than 50 msec), but would not limit it to that minimum. In essence, this capability of the brain would enable the smoothing of memory and thought transitions from vignette to vignette. Persistence does not preclude sensory stimuli from appearing different to us if the actual input occurred simultaneously vs. separate in time (but within at least 50 msec). On the contrary, there are differences in tone and pitch of sound bites that are temporally separated by more than 15 msec. However, persistence will prevent the perception that each short stimulus (within 50 msec) appears discrete from its temporal neighbor. Persistence, as a feature of memory, would occur as a natural consequence of both ongoing sensory stimulus and the quenching or recovery times of neural nodes post stimulus. Whether or not neural nodes are electro-chemically induced or otherwise, there is an expected decay time post stimulus that is associated with the process and this would be consistent with the observed general properties of neural networks as well. Studies done with patients awakened from dream sleep stages show that these patients remember their dreams with varying clarity, indicating that neuronal persistence is indeed at work. In studies of various memory systems (direct recollection, short term recall, etc.) measured event related potentials have indicated windows to total awareness of times ranging from 350 msec to 1900 msec. Information perceived while unaware can remain in conscious memory for several hours.
The same concepts ring true in the areas of motor activation, when we walk without awareness of a stepping cadence, or drive a car without full awareness of the street details passing by. Some neuroscientists label this peripheral focus or absolute focus as part of a variable called “attention,” but we would need to distinguish carefully between what is in our purview to “attend to” and what is not. The portion of consciousness that is forever in the unaware cycle cannot be the focus of conscious attention, because it will not yield to any level of concentration. Attention, as such, is a tool we use within the aware cycle to bring focus to one or one set of facts or events preferentially over another. By excluding others, or relegating them to subordinate roles, we are setting up the pieces that count in the complex thoughts that humans exhibit. Part of this facet of continuous consciousness contains what psychologists refer to as the subconscious. That term can be misleading though, because there is a suggestion that you can remember something or address something directly that is “just below the surface of awareness.” This would only be true if one were to have contact with those intimate details and the mechanics of unaware thought—apparently not obtainable, since those mechanisms of the unaware processes are not subject to direct recall. As conscious awareness is but a fraction of the rapidly repeating and interleaved conscious cycles alternating between aware and unaware, and details of these unaware dynamics are not available within awareness, then the concept of a classical “subconscious” might have little meaning within this description. During the two phases of consciousness, aware and unaware (which is the sum total of all our conscious experience), we become conscious of everything around us that our sensory capabilities may have been stimulated with. We are only cognizant during the aware cycle, and thus have limited verbal reporting ability concerning the whole scene or everything we have sensed. It would then appear as if our brain “filled in missing details,” but that would not be the case. Rather, we always “knew” what was in the scene, but were not “aware” of all of it in the part of the process we verbally report on, which is conscious awareness. Indeed, if we filled all the data in with our brain as a “construct,” the resulting image in our mind would not necessarily comport as closely with actual photographs of the scene or the physical data; it would only be very rough approximations of them. Since we are indeed conscious of all the experiential content within this bimodal cycle, consciousness will appear continuous, despite only reporting on part of it during awareness.
Attention itself is an intended sensory focus on some portion of the data/emotion content of the current aware cycle. For an individual to “attend” to one specific fact, happening or emotion, or a set of the same occurring over many aware cycles to the exclusion of the rest of the scene would, in essence, be the equivalent of placing a blockade, or filter over the totality of the content being recalled during the unaware cycle, and only passing through the germane features matching those “attended” items. The analogy that best fits this picture is when we place a color filter in front of a camera used to take a photo in daylight, we selectively enhance the specific color items within the scene, and remove or diminish others. Attention, as a process, is potentially cued in as a sensory response that rapidly overwhelms the ever present “silent thought” data stream, and can subsequently be enriched by the ongoing cycles of the unaware mode. It is as if this bimodal system of consciousness must focus on something, and provide feedback during our waking moments. Attention deficit may actually be a misnomer, in that attention cues may not be missing or inadequate, but rather too plentiful, with not one of them dominate over the other.
The eyes are typically thought to be under voluntary control, with the responsible cortical areas located within the frontal cortex. However, eye motions occur in two fashions—smooth and slow controlled eye tracking in response to a moving object within the visual field, and in sudden jumps, known as saccades. The saccades themselves are bimodal, that is, there is a set of motions that have very short latencies (less than 100 msecs) known as express saccades, and a set of standard, sudden jumps (3 to 5 per second) that occur with high acceleration and deceleration rates that are for all practical purposes ballistic, even though deceleration is accomplished by simply stopping the input to the agonist (acceleration) muscles. The latter saccade movement (standard motion) is completed in 30 to 120 msecs, and then stays steady in “fixation.” Fixations can last from 200 to 500 msecs. The express saccades, however, miss the visual target more often than the regular saccades, and have unpredictable gap durations. Whereas visual feedback cannot guide saccades, they appear to be guided by internal feedback of representations of a scene and a newly picked eye position. Most of the feedback originates in the superior colliculus. In short, the saccades appear as autonomic motions, with feedback from the mind to correctly re-align them to various targets. They are a collection of motions with trajectories and corrections resembling distributed data systems.
Oculomotor movements and saccades can be essentially both “windows” to conscious timing events, and hallmarks of the aware and unaware state transitions. To demonstrate this potential mathematically, one only need examine the literature for measured event times. These motor movements of the eyes can respond in a tonal fashion to lower frequency signals, and in a “twitching” fashion to high frequencies of up to 150 Hz. As a result of these capabilities, the eyes themselves display several different types of motions, categorically falling into two classes: major saccades and minor saccades.
Major saccades in humans are slow, visually observable motions of the eyes (generally commensurate with head movements) that are larger than 1.2 degrees, and driven by the 5 Hz or less tonal muscle motion. On the other hand, minor saccades can be subdivided into smaller motions, such as mini-saccades or flicks, and micro-saccades or tremors. These latter motions are not visible to the unaided eye, need special instrumentation to be observed, and are governed by the twitch muscles. The larger saccades typically occur over a 3 to 20 sec period, and are generally infrequent. The minor saccades are more regular, low amplitude movements that have been associated with object or group scanning. The most rapid and regular minor saccadic motion are the tremors, which are typically centered at about 90 Hz, but have been measured in ranges between 30 Hz and 100 Hz. Their duration lasts 10 to 20 msecs. The mini-saccades occur at a rate of 3 to 5 per second for a typical duration of 25 to 30 msecs. Both these types of motion will occur during “voluntary” fixation, that is, despite our controlling where our focus (or attention) is centered. Even though the tremors are smaller amplitude changes in eye position, they are enough of a displacement that they should, theoretically, blur vision, but they don't. The mini-saccades have larger amplitudes, occur at theta frequency rates, and have been theorized to be larger corrective displacements to overcome the drifts produced by tremors. Insofar as mini-saccades occur during fixations, and have been correlated to visual attention, their transitions may represent shifts of attention or refocus. Their amplitude and frequency should also contribute to a distortion of experienced visual images, but again, they do not in conscious awareness. The saccades themselves also respond to feedback, that is, there are adjustments made movement by movement to new items presented within the field of view. However, the actual time of movement, taken from the appearance of a new item (target), is smaller than the overall fixation period.
Certain motions of the eye would then offer an opportunity to present diagnostic information about the processing of consciousness content, or better yet, the dysfunctional outcomes due to impaired timing from brainstem regions as reflected in those eye motions. Current studies show that eye micro-tremors can be an indication of the general state of consciousness, including the depth of anesthesia, as the number of tremors become fewer as the individual approaches unconsciousness. Along with the frequency of eye tremors, the latency of saccadic motion, range of motion, and fixation stability are among other changes that can prove to be diagnostic. Saccadic anomalies have been used as part of diagnostic testing of patients with Multiple Sclerosis and Parkinsons Disease. Likewise, other neurological disturbances such as Huntington's Disease and Attention Deficit Hyperactive Disorder (ADHD) have had ongoing research showing correlation of established diagnosis with changes in saccadic eye motion. If, as the new theory developed by the inventor herein suggests, the micro-eye movements are reflections of the autonomic timing for the natural interleaving of the conscious aware and unaware states, then changes in that timing and signature components could potentially be demonstrated as altered or impaired neurological functions. Incomplete aware timing could possibly disturb neurological signs of awareness and attention, and incomplete unaware timing could affect motor neuron transmissions, among other processes.
It is known that disorders such as Parkinsons Disease, Huntington's Disease and Tourette's syndrome share a common region of the brain that is associated with some of the motor difficulties, especially in the basal ganglia. Since the origination of the signals causing involuntary eye motion, and the aware/unaware windows of consciousness are tied through or within similar areas, it can be argued that the direct observation of eye movement abnormalities due to these disorders and the corresponding motor symptom appearances are related. However, since the origination points are within the basal ganglia structures and the autonomic systems, these influences are not occurring through consciousness pathways, just through the timing areas of the brain responsible for the bimodal portions of consciousness, aware and unaware. Typically, the basal ganglia can be responsible for true weakness, as noted in some Disease states. However, such disorders can display a full range of abnormality, not limited to just “weakness” of motor responses. These include affects of the ease and speed of motion. Additionally, both Parkinsons Disease and Multiple Sclerosis patients concomitantly display cognitive changes. Therefore, the observations for these two physical disorders appear to be more complex than just the currently recognized neuro-physical impairments noted in the literature, and could infer correlations beyond the coincidence of similar brain structure involvement. Surely the psychological issues within schizophrenia are more “cognition” issues than motor issues as are those of ADHD. Measurements made on schizophrenic patients have shown demonstrable changes in saccadic reactions concomitant with impaired information processing. Studies on patients diagnosed with ADHD have shown impairment of fixation and saccadic movements as compared with normal patients. Likewise, administering Ritalin (methylphenidate) appears to strengthen saccadic control and weakens strong fixations. Even though the saccadic and tremor eye movements are windows to the autonomic conscious timing events, and not a basic “driver” of the system, this new theory infers that the eye motions are also demarcation movements of the changes of “attention” within consciousness. Insofar as the tremors can be observed as part of the overall eye motion, theoretically, these movements could be studied as to their changes (if any) produced while forcing shifts in attention, or the reverse. This represents a relatively new area for research: to examine if consciousness mechanisms can be used to alter consciousness dynamics.
Since eye motion, attention and ultimately feedback are the major control items within the cyclical consciousness expounded in this model, they are also important to the modification of consciousness. Even though cyclical timing is autonomic, the data elaborated in this paper show that the cycle itself can be disrupted: it occurs in biofeedback, Eye Movement Desensitization and Reprocessing (EMDR), trance and other therapies. The recognition that eye motion represents a physical portal to timing is novel, and can allow for extended research in changes produced by drugs as well as changes accompanying various cognitive aberrations. It is interesting to note that those having ordinary skill in the art have aptly labeled the conscious process as one that contains the feeling of the body's emotional states, and in reality, we indeed feel all that occurs within us, because we are continuously experiencing it while it is integrated with other sensory stimuli. However, we only report on and talk about what makes it into our “awareness.” All of it will ultimately shape how we think, even those portions resident only in our unaware and unattended consciousness because of the regular cycling of the aware and unaware states.
Accordingly there is a need for, and what was heretofore unavailable, a system and method for correlating ocular micro-movement and ocular micro-tremor signals with cognitive dysfunctions. The present invention solves these and other needs.